Water tunnel



April 22, 1952 H, E, SAUNDERs WATER TUNNE ET AL William F. Bra wnE'lLJr.

ATTORNEY.

Patented Apr. 22,01952 WATER TUNNEL Harold E. Saunders, Tak'ma Park, Charles A. Lee, Bethesda, `and Edward A. G. Marvinncy, Chevy Chase, Md., and William F. Brownell, Jr.,

Yeadon, Pa.

Application November 2 5, 1947, Serial No. 788,308

Claims. (Cl. 73-147) (Granted under the act of March 3, 1883, as

The invention relates toimprovements in water ,tunnels and to pipe joints suitable for, but, not

necessarily limited to .use in such tunnels.

An important object of the invention is to provide a water tunnel with a readily removable test section.

Another object of the invention is the provision of a water tunnel having a testsection that may be disconnected and removed without loss of water from the tunnel. v

A further object is the provision of a water tunnel provided with a removable test section so l connected to the tunnel as to not disturb the flow of water in the test section.

Yet another object is the provision of a water tunnel with means for containing water in which the removable testsection of the tunnel may be immersed, and further characterized in that the water-containing means constitutes a load-carrying member extendingr across the'gap produced in the tunnel by removal ofthe testsection.

The inventionA also aims to provide a removable pipe section that may be readily locked inv or released from a pipe line by remotely controllable means.

Additionally, the invention aims to provide a sectional water pipe line so constructed that a pipe section may be removed without loss of water from the pipe line.

ther objects and advantages of the invention will become apparent during the course ofthe following detailed description, Vtaken inl yconnection with the accompanying drawing, forming a part of this specification, and in which drawingf Figure-1 is a view of the Water tunnel, partly in side elevation and lpartly in central vvertical longitudinal. section. 5

Figure 2 is a View of the test section and water tank of the tunnel', partly in side elevation and partly in central vertical longitudinal section.

Figure 3 is a fragmentary sectional view showing a modified form of releasable pipe coupling forming a part of the invention.

Inthe drawing', the numeral IB generally-designates the water tunnel comprising a closed loop supported in a vertical plane by a suitable base I I and framework I 2. In the lower horizontal leg I3 of the loop is an impeller section I4 through which water is circulated around 'the loop in a clockwise direction as viewed Vin Figure 1 One end portion ofthe lower leg ofthe tunnel" is fixed, as by bolting the impeller section to the base II. The other end of the lower leg I3 is supported by a suitable roller bearing. I 5' so as to of the tunnel. For the Same reason, .intermedi-s,

yamended April 30, 1928; 370 O. G. 757) ate supports I6. Il for the lower and upper legs I3, I8, respectively, of the tunnel are adapted to slide on the base II and framework I2. Extending into the tunnel through a. pressure seal I9 in elbow 20 is a propeller shaft 2I provided with a thrust bearing 22 and driven by a motor 23 through a speed reducer 24. The velocity and turbulence of the water leaving the impeller section I4 is decreased by an adjacent diffuser section 25 of uniformly increasing cross-sectional area. Leaving the diffuser section, the water passes through a bottom cylinder 26, elbow 21, upright 28, elbow 29, approach section 33, contraction 3|, test section 32, diffuser section 33, elbow 34 and downflow section 35.

The contraction 3I serves to increase the velocity of the water passing therethrough. Afterwards, the water ows at a constant rate through the test section 32 which is of uniform circular cross-sectional area throughout its length. Beyond the test section, the cross-sectional area of the tunnel increases throughout the length of the diffuser section 33. The purpose of the main diffuser 33 is to recover velocity head of the test section with a minimum of loss and return it to pressure head. The pump then operates to make up the total losses in the system. The diameter of the impeller section I4 is made smaller than that of the lower duct 26 due to pump manufacturers limitations on the size of the impeller for a full scale tunnel wherein the inside diameter of the test section 32 is five feet. Although this arrangement calls for the lprovision of the auxiliary ,diffuser sectionl 25 in the lower leg of the tunnel, it permits the use of a shorter main diffuser 33 whereby the overall length of the tunnel may be reduced. I nterposed between opposite end portions of the elbows 20, 2l, 29 and 34 are suitable guide vane assemblies 36-39 for facilitating the uniform ow of water through the elbows.

Extending between anges 4I, 42 on the contraction 3| and diffuser 33 is an open water tank 43 having its ends rigidly fastened to the anges in a water-tight manner as by gaskets 44, 45 and bolts 4.6. The tank 43 is of a size to permit insertion and removal of the test section 32 through its open top. The test section 32 is normally supported within the tank 43 by joints 4l, 48 that releasably connect the ends of the test section with the contraction 3I and diffuser 33, respectively. The inside surfaces of the contraction, test section and diffuser lie ush and continuous. at the joints 4l,v 48 except. for a small gap allow for longitudinal expansion .or contraction 55.49l at the downstream end of thetest section.

In the example showny in FgureZ, the joint 4l at the upstream end of the test section 32 inf cludes a sleeve 5i) rigidly fastened on an external annular rib portion 5| of the contraction and defining a hydraulic chamber 52 accommodating an annular piston 53. This piston includes a shoulder 54 exposed to hydraulic pressure in the chamber and a forward end portion 55 beveled along its inner and outer margins so as to t in an annular tapered groove 55 in the upstream end of the test section. The joint 41 may be provided with suitable annular packings 51 where desired. Joint 48 at the downstream end of the test section is like joint 4'! except that its piston 53 has a shoulder 54 that is wider than the shoulder 54 of piston 53, and therefore has a greater end surface exposed to hydraulic pressure.

Suitable conduits 60, 6I connect opposite ends of the hydraulic chambers 52, 52 with the lower ends of hydraulic cylinders 62, S3, respectively. Conduits 64, 65 and a two-way valve 66 provide for the connection of any selected one 62 of the cylinders with an air pressure supply line 61 while the other cylinder 63 is vented at exhaust pipe 68.

When the valve 56 ispositioned as shown in Figure 2, the air under pressure admitted to cylinder 62 forces liquid through conduit 60 into the chambers 52, 52 behind the pistons 53', 53'. Assuming that the test section 32 is interposed in the upper leCr of the tunnel, the pistons 53, 53' will be urged toward the ends of the test section, and the beveled forward end portions 55, 55 of the pistons will enter the grooves 55, 56 in the ends of the test section, thus forming rigid watertight joints between the test section and the contraction and diffuser sections. The test section is preferably of a length slightly less than the distance between the contraction and diffuser sections so as to facilitate the insertion and removal of the test section, and to allow for expansion and contraction of the tunnel. Inasmuch as the piston 53' has a greater surface exposed to hydraulic pressure, when the two-way Valve 65 is positioned as shown in Figure 2, a greater force will be exerted against the downstream end of the test section so that the gap 4S will always be located at the downstream end.

Upon turning the valve E3 from the position in which it is shown through an angle of 90, pressure will be applied at the forward sides of shoulders 54, 54', via conduit 65, cylinder 63 and conduit Si, so that the pistons 53, 53 will be retracted from engagement with the test section. The test section can then be lifted from the tank 43 to facilitate the removal, insertion or adjustment of equipment and test bodies therein. By providing the test section with suitable observa.` tion ports lo, cavitation and flow characteristics about models of underwater missiles, submarines, airplanes and wingsA may be observed and photographed.

Suitable valve-controlled water supply and drain pipes ll, 'i2 are provided in the lower leg of the tunnel, and another valve-controlled pipe 13 is connected to the upper leg of the tunnel, preferably at the top of the approach section 30. By connecting this pipe 'I3 to a suitable vacuum pump (not shown), the-pressure of water in the tunnel can be varied and air separating from the water can be drawn off. Ordinarily the tunnel i will be operated with the tank 43 dry, it being necessary to ll the tank only when the test section 32 is to be removed without draining the upper leg of the tunnel. The tank i3 constitutes a load-carrying member extending across the gap produced in the upper leg of the tunnel by rcmoval of the test section 32.

In Figure 3 is shown a modified form of joint 14 differing from the joints 41, 48, first, in that the forward end portion 15 of its piston i6 is beveled only at its inner marginal edge, and second, in that the end of the test section is reduced to provide a beveled shoulder 'VI against which the beveled end 15 of the piston is adapted to seat.

Various changes may be made in the forms of invention herein shown and described without departing from the spirit of the invention or the scope of the following claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

We claim: y

1. In a water tunnel, ducts forming a loop in a vertical plane, one of said ducts in the upper portion of the loop being of reduced diameter and releasably connected between spaced ducts of the loop to complete said loop as a closed hydrodynamic tunnel and constituting a removable test section, a water tank having at least one lateral observation window and constructed and arranged to completely envelop said test section, said tank having a top opening larger` than the test section, said spaced ducts extending into the tank, the top of the tank being above said upper portion at such a height that the test section may be removed upon iooding the tank without loss of water from the spaced tunnel ducts.

2. In a closed vertical loop water tunnel, a water tank having a top opening, tunnel ducts forming the upper portion of said loop and extending into the tank and spacedv to form a gap, a test section having a transparent observation window and disposed in the water tank being releasably connected to said ducts so as to close said gap, and rigid sealing rings constructed and arranged at the respective ends of said test section in sealing relationship to the ends of the ducts, respectively, said rings being forced into and away from said sealing relationship hydraulically, means supplying hydraulic pressure to said rings at each end thereof, and conduit and valve means controlling the relative pressures at said ends, respectively, of the rings for engaging and disengaging the sealing rings, the top of the tank being at such a height that the test section may be removed upon flooding the tank without loss of water from the spaced tunnel ducts.

3. In a water tunnel for use in conducting hydrodynamic tests and experiments, means impelling a stream of water through the tunnel, a water tank'having a top opening, said tunnel including upstream and downstream ducts eX- tending into the tank and spaced to form a gap, a test section disposed in the water tank between said upstream and downstream ducts, the length of the test section being slightly less than said gap, sleeves carried by said upstream and downstream ducts and slidable longitudinally thereof into releasably locking abutment with the test section, means urging the sleeve carried by the upstream duct into abutment with the test section at one end thereof, means urging the sleeve carried by the downstream duct into abutment with the test section at its opposite end with a force greater than that exerted on 5 the sleeve carried by the upstream duct whereby the discontinuity between the test section and the remainder of the tunnel resulting from the slight difference in length of the test section and the gap between the upstream and downstream ducts will be maintained at the downstream end of the test section.

4. In a water tunnel for hydrodynamic testing, a Water tank having a top opening and adapted for observation therethrough, upstream .f

and downstream ducts extending into said tank leaving therebetween a gap, a test section disposed within said gap and having an observation window therein, sleeves carried by said upstream and downstream ducts, respectively, and slidable longitudinally thereon into locking abutment with said test section, means urging said sleeves into abutment with the test section, said means urging the upstream sleeve more strongly thanv the downstream sleeve, whereby any residual gap between said section and said ducts is maintained at the downstream duct.

5. In the water tunnel of claim 4 wherein said means comprises hydraulic pressure lines communicating with one end of each said sleeve, further means controlled by said pressure lines and a manually operable valve for reversing the direction of force applied to said sleeves, whereby the test section may be released from locking abutment.

HAROLD E. SAUNDERS.

CHARLES A. LEE.

EDWARD A. G. MARVINNEY.

WILLIAM F. BROWNELL, Jn.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 1,627,044 McGeehin May 3, 1927 FOREIGN PATENTS Number Country Date 323,652 Germany Aug. 23, 1920 

